IL-18 blockade is a potential disease-modifying therapy for rheumatoid arthritis

Cytokines in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic disease characterized by synovial inflammation that leads to the destruction of cartilage and bone. In the last decade, there was a lot of successful research in the field of cytokine expression and regulation. It has become clear that pro- and anti-inflammatory cytokines, derived predominantely from cells of macrophage lineage, play a major role in the initiation and perpetuation of the chronic inflammatory process in the RA synovial membrane. Monokines are abundant in rheumatoid synovial tissue, whereas low amounts of lymphokines are found. The involvement of pro-inflammatory cytokines, particularly interleukin (IL)-1 and tumor necrosis factor-alpha, in the pathogenesis of RA is well accepted. Recent data provide evidence that the pro-inflammatory cytokine IL-18 plays a crucial role in the development and sustenance of inflammatory joint diseases. There also appears to be a compensatory anti-inflammatory response in RA synovial membrane. It has become clear in the last few years that T cell-derived cytokines expressed preferentially by Th1 cells contribute to joint destruction and inflammation in RA. However, products from Th2 cells may be protective.

Immunotherapy for rheumatoid arthritis

Recently published studies confirm that the long-term use of biological agents targeting TNF-alpha in therapy for rheumatoid arthritis (RA) gives rise to sustained improvement in symptoms and signs of disease, and in the quality of life. Furthermore, it has emerged that anti-TNF therapy protects joints from structural damage, which unexpectedly is also observed in the patient population showing no apparent benefit in control of signs and symptoms. Therapeutic benefit is observed in established disease that is unresponsive to conventional DMARDS and in early DMARDS-naïve RA patients. Thus, for patients with RA, anti-TNF therapies set a new standard for symptom control and joint protection.